For about a year now, I hear a fog horn sound when the water is running. Most of the time it is either when a toilet is being flushed and sometimes it is when the washing machine when it fills up with water. The sound is constant and the only way to "turn it off" is to turn on a faucet and it goes away. If I turn the faucet back off the sound will continue until the toilet is done filling up and then it goes away until the next time I flush the toilet.

I have heard of "water hammer", but I have read that it only happens when the water is off and it is due to turning the water off and then the pipes not having an air bubble to absorb the pressure. This, is kinda opposite in that it only makes a sound when the water is running and the sound is constant.

I have tried and tried to find the source of the sound and I have no idea where it is coming from and to be honest with you I don't even know if it is only happening in one location. I also have tried to make it stop by turning the hot water on, but I don't know if that does anything or not as when I turn the faucet on the noise stops do I don't have a chance to test that out.

One more thing I just remembered is that before the noise, when I would flush the toilet and take a shower the shower temp would not change at all, but for some reason now when I flush the toilet it seems that the temperature in the shower is hot and then changes to a little bit colder when the toilet fills up again. I don't know if this has anything to do with the problem just something I have noticed.

And I just remembered two more things; One, I have changed the internals on two toilets such as the ball cock and flusher as well as completely replaced an entire toilet. Again, I don't know if that has anything to do with the problem, but I just wanted to let you guys know.

The very last thing is when I turn on the hose outside sometimes the water spurts out like there is air in the pipes. I have also heard it make a noise from the hose too, but not that much.